Problem#

Controller failure. No usable metadata. 24 SSD RAID-6 array with VMFS volume.

Constraints#

  • No original controller (but same model available)
  • RAID config: 23 active disks + 1 hot-spare
  • No reliable config data
  • High risk of data loss

Approach#

Treat the system as a black box:

  • Clone all SSDs (time-consuming, but required to preserve state)
  • Analyze stripe patterns and controller logs to identify the hot spare
  • Attach cloned SSDs to a compatible controller (excluding the hot spare)
  • Use controller reconstruction features where possible
  • Manually reconstruct RAID geometry based on header analysis

Outcome#

  • Array successfully reconstructed
  • No significant data loss (VM fsck required)

Notes#

  • Cloning before any attempt was critical to avoid irreversible damage
  • Controller metadata is optional if underlying structure is understood

Key Insight#

Never trust the controller. Trust the data layout.